The present invention relates to an ink jet recording device for printing by ejecting hot melt ink on recording paper.
Communications devices, such as facsimile machines, and information processing devices, such as personal computers, usually have a recording device capable of recording data on recording paper in order to record text and image data as visual information. A variety of recording devices, such as impact type, thermal sensitive type, and ink jet type recording devices, are used. Recently, ink jet recording devices using hot melt ink have drawn more attention because of capability of printing clear images on various quality recording paper quietly.
Conventionally, a recording head of the above-described ink jet recording device is provided with a DC heater for heating hot melt ink which is solid at room temperature. The hot melt ink becomes a molten state when heated by the DC heater. The molten-state ink is ejected from nozzles in the recording head onto the recording paper while moving the head in a main scanning direction. The ink cools down rapidly and solidifies after ejected on the recording paper, so that the ink does not run into the paper and thus is not blurred unlike liquid inks. A high quality image can therefore be obtained with the hot melt ink.
In the conventional recording head described above, the thermal output of the DC heater is set to maintain the ink in a molten state but not set to melt the solid-state ink. For example, a DC 40V is applied to the DC heater. Such a low-voltage DC power source cannot generate large thermal output. Therefore, it requires a long period of time (for example, 20 minutes) for the DC heater to melt the solid-state ink after the recording device is powered. A DC heater generating a high thermal output can shorten the waiting time t the time of startup. However, such a DC heater requires an enhanced DC power source capable of supplying a high level DC voltage. The use of the enhanced DC power source increases the cost of component, resulting in an increase of the entire cost of a recording device.
The use of an AC heater requiring no power source does not invite an increase of cost. However, to do so, a reinforced wiring of a dual insulation structure needs to be used in a power supply path in order to satisfy various safety standards, e.g., UL standard. When the AC heater is moved in a main scanning direction together with the recording head, scanning is likely destabilized because of the reinforced wiring. Also, because the wiring is directly connected to a commercial power supply, malfunction due to external noise more likely occurs during scanning. More seriously, when a 100V AC power source is used, the thermal output generated by the AC heater is too high to achieve fine control of the ink temperature.